Method of and apparatus for making conduits by extrusion



Now 11, 1930. -.1. c. EHERMAN 1,780,948

METHOD OF AND APPARATUS FOR MAKING GONDUITS BY EXTRUSION Filed Aug.

"III-Inn m/ZW am a: glam Patented Nov. 11, 1930 ean 0. ennui/IAN,

or scanner, MAINE, Assrenoa tro Bnown coivrrAnY, on NEW HAMIESHIRE, noon-none'r ox or AIN I Bnnmn,

' METHOD ornn'n ArPAnArus roe. Maxine connurrs BY EXTRUSION' Applicationfiled August 5, 1928. Serial No. 127,260.

This invention relates to articles formed by extrusion, and a method andapparatus. for making the same, special reference being had to tubing orconduit made by extruding a ;plast1c waterproof compound.

to supply a conduit having these and other advantages as will appearfrom the disclosure given hereinafter. By my invention, I make conduitconsisting of fibers with which is incorporated a cementitious orplastic binder preferably of a type which hardens, upon cooling. Anykind of fiber may be utilized such for example as rag or asbestos fibersor a mixture of these with each other or with other kinds of fiber. Theplastic binder may con- 510 sist of asphalt, pitch, wax, oilor anyequivacially when used with a suitable amount of lent material whichsoftens under the ac tion ofheat or can be vulcanized. I have found thatpartially oxidized linseed oil is a binder which has excellentproperties espefiowers-of-sulphur to harden it. Inorder to obtainmaximum qualities of strength, toughness'and durability, I use-fromsixty to seventy-five per cent. of asbestos or other fiber 80 combinedwith forty to twent-y-five-per cent.

of partially oxidized linseed oil. In addition to the sulphur. I alsomay add a small amount of lamp black to impart a smooth grain andexternal finish to the conduit.

This materialwhen set can readily be turned in a lathe or threaded.Instead of a thermoplastioor vulcanizable binder, I may use cements, ifdesired, such cementitious material being suitably mixed with otheringredients to form a thick. plastic mass which can be extruded throughan orifice and will hold its shape. With thecement I may mix sawdust,wood flour, crushed coke, or any other finely divided materialsuitablefor the purpose.

The cementitiousbinder may comprise such substances as silicate of sodaand lime which with sawdust will harden into a: water-resistant body. I

y Inmixing the plastic mass of fiber and binder for extrusion, Ipreferably grind the Face-j T fibrousmaterial, such as old rags orasbestos I mill waste-or the like, on heated rolls with sufficientadhesive material to keep the mass on the rolls. The grinding breaks upthe fibrous materialand works the adhesive binder thoroughlyinto thefibers.- More adhesive binder is thenaddeduntil the desired proportionsof fiber and adhesive are ob,- tained- This results in a' farmorethorough impregnation of the fibrous body With the water-proofingbinder than can possibly be obtainedwhere a tube orother object is firstmade of fibrous material, as forexampleby rolling upa'sheet of paper orbyforming a fiber tube directly-from a Fourdrinier roll, and thensaturating thedried fibrous tube with waterproofing compound. This isevidenced by the fact that where fibrous tubes are made and subsequentlysaturated, the sat;

uration is most complete in the "cases where v the fibers constitutingthe tube have been most completely destroyed in the process of makingthe tube, as for example where the tube is I made of newspaper fiber orground wood. I Vhile by my process the grinding of the fibrous materialon the rolls destroys the fibers to a small extent, yet the intimateintermixture of'theplastic binder with the fibers during the process ofrolling produces a high degree of saturation or-impregnation of thefibrous structure with the adhesive with a relatively small degreeofdestruction of the fibers.

- Further advantageous featuresof my in-' scription and on the drawing,of which 2+ Figure 1 is perspective of a length of conduit formedaccording to my invention.

Figure 2 is a diagrammatic elevation of apparatus for carrying out theinvention.

Figure 3 is a sectional detail of a part of the apparatus shown in;Figure 2.

Figure 4 is a fragmentary view of alength of conduit on which a sleeveof waterproof material has been formed by extrusion.

Figure 5 is a modified form of the apparatus shown in Figure 3 adaptedto extrude a sleeve upon a core, as shownin Figure 4; 3

Figure 6 is a fragmentaryview of .a section of conduit having a liningextruded therein. 7 1 T vention will; appear from the following de feo vrFigurg i a modifiedf rm of apparatus forv extruding the lining, asshown n I Figure 6.

' Figure 8' is acrosssectional View ofa multiple conduit which can beformed by extrusion;

I Referringhto the drawings in 'detail lO -represents ahopper throughwhichithe raw -inaterials may beyfed to a pair ofrolls 11- which areheated asby steam pipes 12 and driven by [any suitable means (notshown). The fibrous material, such as rags or asbestos V mill waste, aremixed with sufficient adhesive Qmaterial, such as partially oxidizedlinseed oil with or Without rubber or other equivalent, and fed to therolls 11 through the hop per 10.; After athorough grinding of themixture on the hot rolls,more-adhesive to gether with a suitable amountof fiowers-of- ,4 1 sulphur, powvdered mica and lampblack,

desired, is added to the mixture on the rolls to form a: soft, workablemass of proper con-' 1 sistency." Whenthefmass has been thorough-:

'ly'intermi'xe'dfit' is'fscraped from the surface of the rolls andallowed todrop' down through ,a hopper 13 which opens fa'sjat let intoasuitable'cylinder 15 hich-is preferably steama This press ina'ybeofa-nydesired type such j acketedat" 1 6jto niaintain'itat a suitabletenaper'ature, Injorde'r' to i apply pressure to the plastic mass forthe purposes of extrusion, I- provide a piston1'7 which'may'be raised orlowered'by any desired means, such 'asa screw shaft or a hydraulic pressindicated at: 181

' ascan be boughtonthe open market suitable mass may be extruded;Inorderto providei I j for the hollow center of the tubular'conduit,

preferably extends to the further wallof the {for the servicerequir'ed;*An'extrusionorifice 19 is formedat any suitable point ina wall ofthe*"cylinder15,' through which the plastic I locate in the-orifice19a'mandrel 20 which cylinder 15.' This mandrel 20 is; preferably ahollow for purposes to' be described,and is I "supported by any suitablemeans, such as strut-s or fins 191, preferably located near themou'thoffthe orifice 19. Multiple conduit 7 sucha's that'illustr'ated inFigure 8 {Canbemade by" shaping the orifice inaccordance withgthe'desiredoutline ofthe cross section;

This may be as'illustrated to 'minimize Weightand-cost of materia'L-ormay be rectangular or any other desiredshape.

[may extend through the orifice and be sup- A number of mandrels 20, onefor eachduct, in the conduit,

ported in spaced relation to the sides of the 1 'oriliceand to eachother.

When plastic mate-rialioff the naturedescribed is extruded int-o theopen air, it has av tendency to: cool rapidlyand to shrinkslightlyltoward th'e n edian line of' the material. The cooling isusually more rapid on the outer surface" 1 than the inner. surface and[consequently internal strains are set up'in' the material "which renderthe conduit brittle and liable to crack. Another frequent cause of outerend of the member 21.

"rate from suchsurfaces. I

brittleness of conduit of this type is the ten clencyv of the extrudedmaterial to form in" V laminations under the influence of pressure usedin forcing the 'Inaterial through; the orifice. Such laminations are aptto form} in planes substantially normal to" the applied pressure,instances of this tendency innature.

being fOllIlCllll the case ofslateandsha'le tormation.- Inorder toproduce aconduit of maximum durability andminimum fbrittle ness, it isnecessary first to'use proper materials in c orrect;proportion; second,to'mix to apply the pressures on the-material in the course of extrusion1n such a way as to 1mmmize t-he tendency 'to laminate in anyone theingredientsthoroughly and evenly third,

direction; and fourth,tocontrol 'the cooling of the mass in such away astoavoid the;s etting up of internal stresses'in the material .off-

the conduit. I provide for the first twdof these considerations, abovementioned,- I by selecting ingredients as hereinbefo-re describedand bymixing the-same onthe steaniheated rolls ll. :Inorder; to-provideagainst unduela-minations in any onedirection, Iiproform ed integrallywith a wall of the cylinder 15; and extends outwardly from'theorilice l9r with a constantly decreasing diameter.' This member 21' also surroundsand is c'oncentrlc with the mandrel '20; The function of the member21 vis to causethe plastic mass'whi'ch a lol'igitudinal pressure whichcauses the mass to move forward, a radial reactive pressureis developradial laminations. =I may also ac-- complish "the same purpose bygiving the member 21' a cylindrical shape, but tapering the mandrel 20in the other" directionso that it increases in diameter to its maximumat the iIn orderfto preventtheflex'truding tubing from pilingup'ontheimandrel 20 as it might supplied by thejtap'er ofthemeniber 21whicli" i prevents excessive tendency 0f the massto do if allowed "to"emerge, from the narrowest Y a portion ot the member. Zliht'o'the openair I'provide a cylindrical extension- 2201 the member 2 1 which ispreferably formed-fin-jj tegrally therewith and'is also concentricwiththe mandrel 20; The mandrel 2 0 and the extension 22 are 1 constructedof suitable" length to maintain' the conduit inproper shape whileit setssufficiently to .hold its j shape as it leavestheendyof theextension.The surfaces of the mandrel -20 and the ex tension-22 on which theextruding mass slides are preferably of 'polished steel as plastic 5mixtures of the class described readilysepa a a In order to providefo'rsuitable temperature control so as to enable the extruding vide'aconical member a 21 which may the,

conduit to cool in a manner designed to leave I it with the leastpossible internal stresses, I

.course of extrusion until it reaches the second compartment 24 which ispreferably maintained at a somewhat lower temperature. The compartmentis maintained at a still lower temperature, the extension 22 having nojacket at all. As an example of the temperatures at which thecompartments may i be maintained when a conduit is being made of amixture of fiber and partially oxidized linseed oil with sulphur, aspreviously described, the steam jacket 16 and the compartment 23 may bemaintained at a temperature I of approximately 250, the chamber 24 atabout 200, and the chamber 25 at about 100. These temperatures may bemaintained by any suitable means, such as steam and water, heated air,oil or other fluid, or by electric resistance coils. The heated fluidmay be fed through the various chambers as by suitable inlet pipes 26,27 and 28 for the respective chambers and by corresponding outlets 29,.

30 and 31. In the cooling of the conduit, it

is found advantageous to allow the interior surface of the conduit tocool somewhat more rapidly than the exterior surface. To this end Iintroduce into the hollow mandrel 20 a suitable pipe 32 which may passthrough the closed end ofv the mandrel 20 and extend to any desireddistance within the mandrel. An outlet 33 is placed at the end of themandrel so that air which is introduced at a suit able temperaturecirculates from the open end ofthe pipe 32 and travels back through theconduit 20 and out through the exhaust pipe 33. The temperature of theair or other fluid which is introduced through the pipe 32 is preferablyat or slightly below the melting point of the adhesive used in theextruded material. This serves to bring the material near the innersurface of the tube close to the congealing point before the temperatureof the material near the outer surface has been reduced to that extent,so that the tube hardens from the inside out. This process is dulyretarded by the heated jacket and the extension 22 which is warmed bythe material itself, so that internal stresses are largely avoided, butby the time the tube has reached the open air at the end of the mandrel20, it has sufliciently set to hold its shape and to complete thehardening process without becoming brittle.

As the conduit 34 emerges from the extension 22, it may be cut ofi byany suitable" means into the desired lengths "and carried: off as by aconveyor 35;

This method of extruslon is 'capable of beijng used to form a coating 011a pre-forme'd tube of the same or of different material, such as ironor fiber pipe, or'it maybe used to form a liner in such a pipe. For thispurpose, I'may use a cylinder15' and fa" tapering extrusion member 21constructed as previously described, and illustrated in Figures.

5 and 7.- The extrusion members 21 are'prejf erably jacketedfor-temperature c'ontr'oL the' chamber 24 in these cases being shown. as

also connected with the jacket lfi in order to maintain the mass at itsextrusion tempera ature until a later pointis reached than" in the'caseof the'extrusion'of-plain conduit. This keeps thewm'ateri-al'; moreplastic and enables it toslipxmore readily :0n the pipe or core 36"onwhich the plastic'materiallis to form asleeve or'covering layer. Asshown in Figurei5, a ma ndrel 37 is provided withla' suitable shoulder38, this shoulder being formed to receive the end ofa' pipe-36 {overwhich the plastic material is togbe extruded.

The further steps of extruding'tlie mass over? the pipe 36'are aspr'eviou'sly describedfolfthe making of plain; conduit. As shown in:Figure 4,."the finished product comprises the pipe or tube'36withasubstantial'evenlayer 39of-the plastic material covering-'its'upperi surface. In like manner, a liner 4010f plastic mraterial maybeformed in a t-ubeorpi'pe41 by forming a shoulder 42, as shown in Figure' 7 in the'inner wall of the e-xtension;22,soa

t at-the pipe ermav be-inserted .intothe extension 22cagainst theshoulder 42 and the plastic material will a be extruded between themandrel 2O 'and the pipe 41. The'pro'cess of coating or? lining pipes,as illustrated in Figures 4*and 6', is intermittent, the'extrudingpressurein the'cylind'er- 15 being applied after a pipe'is put inposition against the shoulder 38 "or 42 and beingremoved when theplastic matter has been squeezed throughto the 'further'endxof theeXt'ens-ion22, after.

which the lined'or coated pipe may drawn and another] one inserted. a; p

. Having thus described anflembodiment of. my invention, itshouldbegevident to those skilled inthe art that many changes andmodifications may be made therein without departing from its spirit orscope as defined by the appended claims. "Iclaim: v

1. The method of making tubular conduit, which comprises, hot-grinding-rags with a thermo-plastic binder, and extruding the massintubular-form. i

2, Themethod of making tubular conduit, which compriseshot-mixing fiberswith a waterproof plastic binder, and extruding the mass in the formof'a-tube, the walls of theijtube in the jlcourseof extrusion being Iituhe mo'r'e rapidly than-,the'outer surface.

signature.

i jackets about said shaperfml m a s f lf s pt it rately supplying saidjackets with fluids, A

y whereof I- have afiixed my,"

- I In testimon Y 4;;Apparatus forniaking conduit by 'ex- 3 l J Itrusion, {comprising j an, extrusion chamber ltud-inally thereoflftheclearance between the;

wallflof I'the chamber and the core prog'res- 7 'sivellyzand graduallydiminishing in the-dia} re'ctiofnk-of extrusion, and means for pro-,

gressively coolingtheconduit inthe course. mot extrusion; I e y a '5 aThe method of making tubular conduit,

whlchsgcoinprisesfl heating and grindingja ql' antitygof fiber with athermoplastic bindery; extrudingzthe hotmixture into tubular shape,

.which -r comprises" hot-mixing t fiber and a: ,*binderito"form;aplastic mass, and extruding cooling-the inner'surface ofthe tube quickly.toIthecongealing point, and cooling the ex terior' surface of the tubemore slowly;

' the massiintoj tubular' form; thethickness of '30; withinzduringextrusion :theredf- V the ltubefwalls being gradually decreased and thetube-being. progressively cooled from Themethodofmaking tubulariconduit;I Q 7 d I of extrusion beingrapidly cooled from with V Which comprises'hot-mixing' fibe'r" and a binder into a plastic mass, -.andextrudingthe i t mass, into tubular form the tube in the course ei inf and slowlycooled from'; without;

' 8."The'1method of makingtubular conduit, 'which'zco'mprisesz hotmixin'g' fiber and 5a 10;

binder into a plasticmass, and extruding the 7 mass into tubular form;the tubein the course a of extrusion being rapidly cooled from withinand slowly cooled from without; and having its thickness of wallgradually decreased.) 45" i9i*Apparatus for making conduitcomprising; a' container having an orifice, a core ex? truding plasticmaterial through said orifice .'tending-throughsaid orifice, means forextinto tub'ularIfo'rm,-V a tubular 'shaperextend ing from-{around sadorifice and surround- ,lng said core, saldjshaper having'a't'aperinginternalidiameter 'With its maximum diam a 7 v I ete'r adjac'e'nt. tosaid orifice,"and m'eans for w lna'intainingend separately controlling aseries of temperature zones along said shaper;

10. Apparatus for making conduiticom prising a'c'ontainer having anorifice, a core extending through said orifice, means for extrudingplastic'lnate'zrial through said orifice into tubular formyatubularshaper extending from said orifice and surrounding said core, saidshaperhaving a tapering lIl-f ternal diameter withfits maximum diameteradjacent said orifice, a series of peripheral

